Letters of Note: The Masked Letter
Written by a frustrated Lt. General Sir Henry Clinton during the Revolutionary War in 1777, this beautifully crafted Masked Letter is a perfect example of early coded correspondence. The letter reads perfectly well on its own, however only when you place a mask over the paper does the true meaning appear. Incredibly clever, and surprisingly successful as both the letter and mask were sent to the recipient (in this case John Burgoyne) along different routes.
What’s almost as fun as shooting things (or blowing stuff up)? Watching someone else do it in slow motion. 1 million frames per second, for 10 frikkin’ minutes
Bullets liquifying is pretty neat. Bullets getting dented with shrapnel from other impacts is pretty neat, too (can’t recall the CSI franchise using this one — yet — to prove that a particular bullet wasn’t the first one to be fired). Watching cracks in glass propagate is cool, too — it happens much faster than the bullet motion, but then, the speed of sound is the proper metric for motion in these cases (bullet speeds are of that order, and crack propagation is limited by that value), and the speed of sound is much higher is solids than in air. A million frames per second also means you can watch the bullet rotation as it passes through the field of view.
If you were to travel 2000 years into the past, how useful would you be in jumpstarting technological advancements? This 10 question quiz will help you figure out your technological usefulness. If you do poorly on the quiz, as most people likely will, then just let that inspire you to study up more on how things work and where raw materials come from.
I got 8/10. I don’t know engines and I didn’t know how to vulcanize rubber.
Superconductor World Record Surpasses 250K
Superconductors.ORG herein reports the observation of record high superconductivity near 254 Kelvin (-19C, -2F). This temperature critical (Tc) is believed accurate +/- 2 degrees, making this the first material to enter a superconductive state at temperatures commonly found in household freezers.
As a point of reference, dry ice sublimates at about 195 K
Update: Probably a case of “nothing to see here, move along.” I missed some lack-of-credibility signs.
The Collider, the Particle and a Theory About Fate
I’m not talking about extra dimensions of space-time, dark matter or even black holes that eat the Earth. No, I’m talking about the notion that the troubled collider is being sabotaged by its own future. A pair of otherwise distinguished physicists have suggested that the hypothesized Higgs boson, which physicists hope to produce with the collider, might be so abhorrent to nature that its creation would ripple backward through time and stop the collider before it could make one, like a time traveler who goes back in time to kill his grandfather.
Update: Good discussion of why this is crazy, but not crackpot, over at Cosmic Variance
Hot soup in a thermos is surrounded by a vacuum between the inner and outer walls, which prevents heat from conducting directly through the sides, as it would if the walls were a one-piece solid. But the soup still loses heat by “glowing” in infrared light because the light radiated through the walls takes energy away with it.
Shanhui Fan of Stanford University in California and his colleagues wondered if photonic crystals–periodic structures famous for blocking narrow frequency ranges of light–could block the broad range of infrared frequencies radiated by a warm body.
Cosmic Variance: A New Challenge to Einstein?
There is a straightforward way, in principle, to measure these two types of curvature. A slowly-moving object (like a planet moving around the Sun) is influenced by the curvature of time, but not by the curvature of space. (That sounds backwards, but keep in mind that “slowly-moving” is equivalent to “moves more through time than through space,” so the curvature of time is more important.) But light, which moves as fast as you can, is pushed around equally by the two types of curvature. So all you have to do is, for example, compare the gravitational field felt by slowly-moving objects to that felt by a passing light ray. GR predicts that they should, in a well-defined sense, be the same.
We’ve done this in the Solar System, of course, and everything is fine. But it’s always possible that some deviation from Einstein shows up at much larger distance and weaker gravitational fields than we have access to in our local neighborhood. That’s basically what Rachel’s paper does, considering different measures of the statistical properties of large-scale structure and comparing them to the predictions of a phenomenological model of the gravitational field. A crucial role is played by gravitational lensing, since that’s where the deflection of light comes in.
Travel has become difficult. Last year, a bureaucratic snafu not only denied me a trip to a conference in Hawaii, but it happened late enough that it kept me from scheduling an alternate trip to DAMOP. I spent the last week with the flu, which forced me to cancel a long-weekend trip to visit some college buddies, and now my plan to give a talk at an AAPT conference has been shot down. The government is operating under a continuing resolution, rather than an actual budget, and apparently this means there is a moratorium on this kind of travel. Not going on work-sponsored travel would essentially mean I couldn’t talk about results from work, which was going to be half of my talk. I’d be limited to talking about things that you could pick up on the streetcorner (but don’t do that … you never really know if that information is any good). Meh. Maybe this is a conspiracy.
